In recent years air pollution has become of greater concern to all. One of the most common sources of air pollution is the combustion products of fossil or carbonaceous fuels. Among the products of most combustion processes are oxides of nitrogen. Nitric oxide (NO) and nitrogen dioxide (NO.sub.2) are commonly found in combustion products. These oxides are formed by the reaction of nitrogen and oxygen in air at elevated temperatures. Nitric oxide, and other oxides of nitrogen, are formed in combustion processes but in turn react with oxygen in the air at ambient temperatures to form more stable oxides such as nitrogen dioxide. For the purpose of describing the present invention the designation NO.sub.x will be used to encompass the various oxides or oxide mixtures of nitrogen. The presence of NO.sub.x in air also promotes photochemical reactions of hydrocarbons creating additional pollution and amog problems. NO.sub.x is formed in essentially all combustion processes and accordingly much attention has been devoted to its elimination, preferably at the source, e.g., internal combustion engines, fossil fuel power plants, chemical plants, and high temperature incinerators.
Various methods and types of equipment have been proposed to eliminate or reduce NO.sub.x from mixtures of gasses at or near the generation point of the NO.sub.x. Generally these methods fall within the following catagories: absorption of NO.sub.x using water or alkali solutions; absorption of NO.sub.x using solid absorbent such as activated carbon, or; catalytic reduction of NO.sub.x. Absorption in either liquids or solids requires the use of absorption towers and maintenance of the absorption medium. The capital expense and upkeep have made the absorption methods economically unfeasible and the use of such equipment in conjunction with individual internal combustion engines is neither economically nor mechanically feasible. Thus substantial studies and efforts have directed toward making the catalytic reduction of NO.sub.x operable and efficient. Examples of catalysts utilized to remove NO.sub.x are to found in U.S. Pat. No. 3,864,450 (hot carbon containing NaOH or KOH); U.S. Pat. No. 3,524,721 (promoted nickel oxide), and; U.S. Pat. No. 3,816,595 (silicon carbide, per se).
While the reaction of the present invention is not known with exactness, it is most probably to be considered in the catalytic reduction category. The methods and equipment previously used in catalytic reduction processes require a filter or bed of catalytic material through which the gas mixture is passed. The filter or bed impedes the gas flow and contributes an undesirable back pressure. Further the filter or bed becomes coated with various combustion products which drastically reduces its efficiency and results in an increase of undesired back pressure. Filtration of hot combustion gasses has not found to be an operable answer to the pollution problem. One of the more positive advantages of the present invention is that NO.sub.x is eliminated or substantially reduced from stack or emission gasses without the use of a filter or catlyst bed thus gas flow is substantially unimpeded and the efficiency of the process is greatly improved.